Seismic Retrofitting: Reinforced concrete shear wall versus CFRP reinforced concrete using pushover analysis

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1 JOURNAL OF MATERIALS AND ENGINEERING STRUCTURES 3 (2016) Research Paper Sesmc Retrofttng: Renforced concrete shear wall versus CFRP renforced concrete usng pushover analyss Y. Ryad a, *, B. Kss b, I. Mran a, M.A. Parron c, R.C.M. Dolores c a Chouab Doukkal Unversty, Laboratore de mécanque et énergétque, FS El-jadda, Morocco b Hassan II Unversty, Equpe de modélsaton et smulaton des structures en Géne Cvl (M2SGC), ENSAM Casablanca, Morocco c Mechancal and Cvl Engneerng Department, Polytechnc Hgh School of Algecras, Unversty of Cadz, Ramon Pujol avenue, Algecras 11202, Span A R T I C L E I N F O Artcle hstory: Receved : 31 May 2016 Revsed : 14 October 16 Accepted : 21 October 2016 Keywords: Sesmc retrofttng Carbon fber renforced polymer Pushover analyss A B S T R A C T Sesmc retrofttng of constructons vulnerable to earthquakes s a current problem of great poltcal and socal relevance. Durng the last sxty years, moderate to severe earthquakes have occurred n Morocco (specfcally n Agadr 1960 and Hocema 2004). Such events have clearly shown the vulnerablty of the buldng stock n partcular and of the bult envronment n general. Hence, t s very much essental to retroft the vulnerable buldng to cope up for the next damagng earthquake. In ths paper, the focus wll be on a comparatve study between two technques of sesmc retrofttng, the frst one s a renforcement usng carbon fber renforced polymer (CFRP) appled to RC elements by bondng, and the second one s a renforcement wth a shear wall. For ths study, we wll use a non-lnear statc analyss -also known as Pushover analyss - on a renforced concrete structure consstng of beams and columns, and composed from eght storey wth a gross area of 240 m², desgned conformng to the Moroccan Sesmc code [1]. Share wall 1 Introducton Among the reasons beyond the ntensve research actvty n ths feld, one fnds the huge need for dagnoss and rehabltaton of pre-code constructons, partcularly n the case of hstorc monuments [2].Other reasons are assocated to the emergence of new desgn approaches, whch are founded on the concept of performance-based engneerng. Normally, loads on these structures are low and result n elastc structural behavor. However, under a strong sesmc event, a structure may actually be subjected to forces beyond ts elastc lmt. Although buldng codes can provde relable ndcaton of actual performance of ndvdual structural elements, t s out of ther scope to descrbe the expected * Correspondng author. E-mal address: rd.yahya@yahoo.com e-issn: X,

2 182 JOURNAL OF MATERIALS AND ENGINEERING STRUCTURES 3 (2016) performance of a desgned structure as a whole, under large forces. Nonlnear statc analyss also known as pushover analyss s a possble method to calculate structural response under a strong sesmc event. The use of the nonlnear statc analyss (pushover analyss) came n to practce n 1970 but the potental of the pushover analyss has been recognzed for last two decades years. Ths procedure s manly used to estmate the strength and drft capacty of exstng structure and the sesmc demand for ths structure subjected to selected earthquake. Ths procedure can be used for checkng the adequacy of new structural desgn as well. The effectveness of pushover analyss and ts computatonal smplcty brought ths procedure n to several sesmc gudelnes [3, 4] and desgn codes [5, 6] n last few years. Pushover analyss s defned as an analyss wheren a mathematcal model drectly ncorporatng the nonlnear load-deformaton characterstcs of ndvdual components and elements of the buldng shall be subjected to monotoncally ncreasng lateral loads representng nerta forces n an earthquake untl a target dsplacement s exceeded. Target dsplacement s the maxmum dsplacement (elastc plus nelastc) of the buldng at roof expected under selected earthquake ground moton. The structural Pushover analyss assesses performance by estmatng the force and deformaton capacty and sesmc demand usng a nonlnear statc analyss algorthm. The sesmc demand parameters are storey drfts, global dsplacement (at roof or any other reference pont), storey forces, and component deformaton and component forces. The analyss accounts for materal nelastcty, geometrc nonlnearty and the redstrbuton of nternal forces. The structures that desgned for gravty loadng are susceptble for damage durng earthquake. Durng a severe earthquake, the structural members are expected to perform a ductle behavor. The structure s lkely to undergo nelastc deformaton and has to depend on ductlty and energy absorpton capacty to avod collapse. Wth ths sesmc forces, ncrease n loads and lack of regular mantenance, a need to renstate, renforce and upgrade exstng concrete structures has been seen n the constructon ndustry n recent years. A varety of techncal solutons has been mplemented for sesmc retrofttng, n ths study we wll nterest at two types of renforcement. The frst technque s renforcement by RC shear wall. Durng an earthquake, the shear walls play a major role n resstng lateral loads for concrete buldngs [7]; they are effcent to dsspate the nduced sesmc energy, and they are desgned to provde not only adequate strength, but also suffcent ductlty to avod brttle falure under strong lateral loads. Shear walls provde also stffness to buldngs, whch sgnfcantly reduces lateral sway of the buldng and thereby reduces damage to structure and ts contents. The use of shear wall structure has ganed popularty n hgh-rse buldng structure, especally n the constructon of servce apartment or offce/ commercal tower. It has been proven that ths system provdes effcent structural system for mult-storey buldng n the range of storeys [8]. In the past 30 years of the record servce hstory of tall buldng contanng shear wall element, none has collapsed durng strong wnds and earthquakes [9]. The second technque of sesmc retrofttng s renforcement of RC element (columns and beams) usng CFRP. In the last decade, composte materals such as the Carbon Fbers assocated wth Polymerc Matrces (CFRP) appled to RC elements by bondng are proved effectve for the protecton and renforcement of beams and columns. S.A. Shekh et al. [10] have nvestgated the sesmc behavor of concrete columns confned wth steel and FRP; they concluded that the use of FRP sgnfcantly enhances strength, ductlty, and energy absorpton capacty of columns. R.D. Lacobucc et al. [11] (2003) nvestgated the retroft of square concrete columns wth CFRP for sesmc resstance; they found that added confnement wth CFRP at crtcal locatons enhanced ductlty, energy dsspaton capacty and strength of all substandard members. In spte of the extensve work on renforced concrete columns, very few researchers have worked on renforced concrete columns strengthened usng FRP. The present paper, nvestgates the effcency of sesmc retrofttng wth a RC shear wall, aganst a renforcement of RC members wth FRP materals (CFRP), usng a Pushover analyss to estmate sesmc structural deformatons.

3 JOURNAL OF MATERIALS AND ENGINEERING STRUCTURES 3 (2016) Non Lnear Analyss (Pushover analyss) 2.1 Defnton The nonlnear statc procedure [12] has become a standard method n structural engneerng practce for performancebased sesmc evaluaton of structures. In the NSP or pushover analyss, the structure s subjected to monotoncally ncreasng lateral forces wth an nvarant heght-wse dstrbuton untl a target dsplacement n reached. The sesmc demands are computed at the target dsplacement and compared aganst acceptablty crtera. These crtera depend on the materal (concrete, steel, etc.), type of member (beam, column, panel zones, connectons, etc.), mportance of the member (prmary or secondary), and the structural performance levels (mmedate occupancy, lfe safety, or collapse preventon). 2.2 Procedure Pushover analyss can be performed as ether force-controlled or dsplacement controlled dependng on the physcal nature of the load and the behavor expected from the structure. Force-controlled opton s useful when the load s known (such as gravty loadng) and the structure s expected to be able to support the load. Dsplacement controlled procedure should be used when specfed drfts are sought (such as n sesmc 2, 1 loadng), where the magntude of the appled load s not known n advance, or where the structure can be expected to lose strength or become unstable. Some computer programs (e.g. Sesmostruct, Nonlnear verson of SAP2000, ANSYS) can model nonlnear behavor and perform pushover analyss drectly to obtan capacty curve for two and/or three dmensonal models of the structure. When such programs are not avalable or the avalable computer programs could not perform pushover analyss drectly (ETABS, RISA, SAP90), a seres of sequental elastc analyses are performed and supermposed to determne a force dsplacement curve of the overall structure. A dsplacement-controlled pushover analyss s bascally composed of the followng steps [13]: 1. A two or three dmensonal model that represents the overall structural behavor s created. 2. Blnear or tr-lnear load-deformaton dagrams of all mportant members that affect lateral response are defned. 3. Gravty loads composed of dead loads and a specfed porton of lve loads are appled to the structural model ntally. 4. A pre -defned lateral load pattern whch s dstrbuted along the buldng heght s then appled. 5. Lateral loads are ncreased untl some member(s) yeld under the combned effects of gravty and lateral loads. 6. Base shear and roof dsplacement are recorded at frst yeldng. 7. The structural model s modfed to account for the reduced stffness of yelded member(s). 8. Gravty loads are removed and a new lateral load ncrement s appled to the modfed structural model such that addtonal member(s) yeld. Note that a separate analyss wth zero ntal condtons s performed on modfed structural model under each ncremental lateral load. Thus, member forces at the end of an ncremental lateral load analyss are obtaned by addng the forces from the current analyss to the sum of those from the prevous ncrements. In other words, the results of each ncremental lateral load analyss are supermposed. 9. Smlarly, the lateral load ncrement and the roof dsplacement ncrement are added to the correspondng prevous total values to obtan the accumulated values of the base shear and the roof dsplacement. 10. Steps 7, 8 and 9 are repeated untl the roof dsplacement reaches a certan level of deformaton or the structure becomes unstable. 11. The roof dsplacement s plotted wth the base shear to get the global capacty (pushover) curve of the structure (Fgure 1).

4 184 JOURNAL OF MATERIALS AND ENGINEERING STRUCTURES 3 (2016) Lateral Load Profle Fg. 1 Global Capacty (Pushover) Curve of Structure [13] The analyss results are senstve to the selecton of the control node and selecton of lateral load pattern. In general case, the center of mass locaton at the roof of the buldng s consdered as control node. The lateral load generally appled n both postve and negatve drectons n combnaton wth gravty load (dead load and a porton of lve load) to study the actual behavor. Dfferent types of lateral load used n past decades are as follows: Unform Lateral Load Pattern The lateral fore at any story s proportonal to the mass at that story. Where: F : Lateral force at -th story m : Mass of -thstorey Frst Elastc Mode Lateral Load Pattern F m = (1) m The lateral force at any story s proportonal to the product of the ampltude of the elastc frst mode and mass at that story. Where: φ : Ampltude of the elastc frst mode at -thstorey Code Lateral Load Pattern F mφ = (2) mφ The lateral load pattern s defned n Moroccan sesmc Code [1] and the lateral force at any storey s calculated from the followng formula: Wh n n Fn = ( V Ft) (3) n Wh

5 JOURNAL OF MATERIALS AND ENGINEERING STRUCTURES 3 (2016) Where: F n : Horzontal force appled to n-thstorey V:Sesmc Base-force W n : Total load of n-th floor h n : Heght of n-thfloor measured from base T:Fundamental perod Ft = 0 s T 0.7s Ft = 0.07 TV s T > 0.7s FEMA-273 Lateral Load Pattern Fg. 2 Vertcal repartton of sesmc forces [1] The lateral load pattern defned n FEMA-273 s gven by the followng formula that s used to calculate the nternal force at any story: Where: F = h : heght of the -th story above the base K: a factor to account for the hgher mode effects (k=1 for 0.5 sec and k=2 for >2.5 sec and vares lnearly n between) Mult-Modal (or SRSS) Lateral Load Pattern n mh The lateral load pattern consders the effects of elastc hgher modes of vbraton for long perod and rregular structures and the lateral force at any story s calculated Square Root of Sum of Squares (SRSS) combnatons of the load dstrbutons obtaned from the modal analyss of the structures as follows: k mh k 1) Calculate the lateral force at -thstorey for n-th mode from equatons (4) Where: F = Гmφ A (5) n n n

6 186 JOURNAL OF MATERIALS AND ENGINEERING STRUCTURES 3 (2016) Г n : Modal partcpaton factor for the n-th mode φ n : Ampltude of n-th mode at -thstorey A n : Pseudo-acceleraton of the n-th mode Sngle Degree Of Freedom (SDOF) elastc system 2) Calculate the storey shears: V n N = F (6) j= 1 jn Where N s the total number of storeys 3) Combne the modal storey shears usng SRSS rule: V = n ( V ) 2 n 4) Back calculate the lateral storey forces,f, at storey levels from the combned storey shears, V startng from the top storey. 5) Normalze the lateral storey forces by base shear for convenence such that F ' F F = (7) The contrbuton of frst three elastc modes of modal analyss was consdered to calculate the 'Mult-Modal (or SRSS)' lateral load pattern n ths study. 3 Law of behavor for FRP-confned concrete The stress stran behavor of FRP-confned concrete s largely dependent on the level of FRP confnement. When axal stress s low, the stress stran response of FRP-confned concrete s smlar to that of unconfned concrete. Whle the axal stress reaches the maxmum strength of unconfned concrete, the lateral expanson of FRP-confned concrete ncreases drastcally, accompaned wth the growth of mcro-cracks. If the confnement of FRP s weak, the stress wll degrade beyond reachng the maxmum strength untl the rupture of FRP. If FRP confnement s strong enough, FRP s actvated after reachng the maxmum strength of unconfned concrete and apples a contnuous ncreasng pressure on the concrete core untl the rupture of FRP. A sharp softenng and transton zone at the stress level of the maxmum strength of unconfned concrete wll be deformed, so the stress stran curve of concrete confned wth suffcent FRP dsplays a dstnct blnear response.typcal stress stran responses of FRP-confned concrete are shown n Fgure3. Fg. 3- Typcal stress stran responses for FRP-confned concrete [14]. In Fgure3, ponts C and D are the ultmate status of FRP-confned concrete where FRP ruptures. Pont A s the peak status of the FRP-confned concrete wth a stran-softenng component. Pont B s wthn the sharp softenng and transton

7 JOURNAL OF MATERIALS AND ENGINEERING STRUCTURES 3 (2016) zone, and named transton status for the stress stran response wth a stran-hardenng component, but t s hard to accurately locate ths pont [14]. 4 Descrpton of the buldng 4.1 Geometry The buldng s a renforced concrete eght storey buldng wth a gross area of 240 m². The buldng heght s 27 m wth 3m n each storey. The RC structure s composed from three bays wth a 4 m n each one. Fg.3 shows the general geometrc arrangement of the structure. The slabs thckness s 25 mm (20+5). The beams sze s 25x25mm. For the columns, there s four types wth sze 40x40, 35x35, 30x30, 25x Materal propertes Weght per unt volume (t/m 3 ) Fg. 4 Dmensons of the buldng (Model realzed on SAP2000) Table 1 - Concrete propertes Modulus of Elastcty E (MPa) Posson s rato U Coeffcent of thermal expanson A Concrete compressve strength f c (MPA) Weght per unt volume (t/m 3 ) Table 2 - Steel propertes Modulus of Elastcty E (MPa) Posson s rato U Coeffcent of thermal expanson A Concrete compressve strength f c (MPA)

8 188 JOURNAL OF MATERIALS AND ENGINEERING STRUCTURES 3 (2016) Sesmc Data Weght per unt volume (t/m 3 ) Table 3 Carbon Fber propertes Modulus of Elastcty E (MPa) Posson s rato U Coeffcent of thermal expanson A Concrete compressve strength f c (MPA) Table 4 Sesmc data of the ste Pods total de la Acceleraton Sol factor Amplfcaton Prorty Behavor structure W (t) coeffcent A S factor D factor I factor K Result and Dscusson The lateral loads appled to the structure are calculated wth Moroccan sesmc Code (RPS2000). The followng table resume the results of the lateral force appled to each floor. Table 5 Lateral loads result Level Base-force (V) Heght of each storey h (m) Lateral force for each storey F (kn) The pushover analyss of the structure s performed usng SAP2000, a structural calculator software that allow us to perform analyss and sesmc desgn of buldngs. The hnges placed on columns s defned to P-M3 type, for beams the hnges are all type M Deformed shape of the structure and plastc hnge formaton Fg. 5 The plastc hnge behavor [15]

9 JOURNAL OF MATERIALS AND ENGINEERING STRUCTURES 3 (2016) Pont A corresponds to the unloaded condton. Load deformaton relaton shall be descrbed by the lnear response from A to an effectve yeld B. Then the stffness reduces from pont B to C. Pont C has a resstance equal to the nomnal strength then a sudden decrease n lateral load resstance to pont D, the response at reduced resstance to E, fnal loss of resstance. The slope of the BC lne s usually taken between 0 and 10% of the ntal slope. The CD lne corresponds to an ntal falure of the member. The DE Lne represents the resdual strength of the member. These ponts are specfed accordng to FEMA to determne hnge rotaton behavor of RC members. The ponts between B and C represent acceptance crtera for the hnge, whch s Immedate Occupancy (IO), LS (Lfe Safety), and CP (Collapse Preventon). Table 6 Performance level of buldng Level Operatonal Immedate Occupancy Lfe Safety Collapse Preventon Descrpton Very lght damage, no permanent drft, structure retans orgnal strength and stffness, all systems are normal Lght damage, no permanent drft, structure retans orgnal strength and stffness, elevator can be restarted, Fre protecton operable Moderate damage, some permanent drft, some resdual strength and stffness left n all stores, damage to partton, buldng may be beyond economcal repar Severe damage, large dsplacement, lttle resdual stffness and strength but loadng bearng column and wall functon, buldng s near collapse The mode of falure of ths type of structure under sesmc exctatons s plastcs hnges formaton. The fgure below show the plastcs hnges formaton for the lateral load and the deformed shape of the three structures: unrenforced, renforced wth shear wall and fnally renforced wth CFRP. (a) Fg. 6.a Plastc hnge formaton n the unrenforced structure (b) Fg. 6.b Zoom on the lower part of unrenforced structure

10 190 JOURNAL OF MATERIALS AND ENGINEERING STRUCTURES 3 (2016) (a) Fg. 7.a Plastc hnge formaton n the renforced structure wth shear wall (b) Fg. 7.b Zoom on the lower part of the structure renforced wth shear wall (a) Fg. 8.a Plastc hnge formaton n the structure renforced wth CFRP (b) Fg. 8.b Zoom on the lower part of the structure renforced wth CFRP

11 JOURNAL OF MATERIALS AND ENGINEERING STRUCTURES 3 (2016) The followng tables show the type of the hnges for each element n the three structures: Table 7 type of hnges for unrenforced structure Step A to B B to IO IO to LS LS to CP CP to C C to D D to E Beyond E Total Table 8 Formaton hnges for renforced structure wth shear wall Step A to B B to IO IO to LS LS to CP CP to C C to D D to E Beyond E Total Table 9 Formaton hnges for renforced structure wth CFRP Step A to B B to IO IO to LS LS to CP CP to C C to D D to E Beyond E Total From the table7, at every step, the unrenforced structure loss n stffness we can see n the last step, there s some element beyond the pont E, whch mean that our structure cannot resst to ths lateral force, n other way, we have to renforce t. In table 8, we appled the frst technque of renforcement; t s a renforcement usng shear wall. The degree of damage s reduced compared wth the frst table, as shown n the second table we have mproved the resstance of the structure, there s zero element beyond pont E and just one element between D and E even. If t s the case, the structure may suffer from several damage.

12 192 JOURNAL OF MATERIALS AND ENGINEERING STRUCTURES 3 (2016) As consequence, we have appled another technque of renforcement. It s the one usng the carbon fber renforced polymer (CFRP), and the result shown n the table 9 s very satsfyng. We have all element under the Lfe Safety zone, whch mean that our structure have an elastc behavor, n other way t can resst wthout any problem to the sesmc force. 5.2 Pushover curves 250 Pushover curve of unrenforced structure BASEFORCE (kn) DISPLACEMENT (m) Fg. 9 Pushover curve of unrenforced structure 300 Pushover curve of Structure renforced wth CFRP 250 BASEFORCE (kn) DISPLACEMENT (m) Fg. 10 Pushover curve of renforced structure wth CFRP 250 Pushover curve of Structure renforced wth Shear wall 200 BASEFORCE (kn) DISPLACEMENT (m) Fg. 11 Pushover curve of renforced structure wth Shear wall

13 JOURNAL OF MATERIALS AND ENGINEERING STRUCTURES 3 (2016) PUSHOVER Curves of the three structures Unrenforced structure renforced structure wth shear wall BASEFORCE (kn) DISPLACEMENT (m) Fg. 12 Pushover Curves of the three structures Roof dsplacement versus base-force s present n the pushover curves for each structures on fgures 9, 10 and 11. As mentoned before, lateral load patterns are calculated wth Moroccan sesmc Code (RPS2000). In vew of the results obtaned n the analyss, the comparson of the pushover curves (Fgure 12) shows that the renforced structure wth CFRP s stffer than the renforced structure wth shear wall. We had conclude ths by; Frstly the storey dsplacements obtaned for the renforced structures by CFRP s lower than the one obtaned for the structure renforced by shear wall, and secondly the ductlty for structures renforced by CRFP s hgher than that for structures renforced by shear wall. The result of dsplacement and the base-force s shown n the follow tables: Table 10 Dsplacement and Base-force of unrenforced structure Dsplacement 0 0,0518 0,1730 0,3033 0,3263 0,3264 0,3292 0,3231 0,3258 0,2450 0,2260 0,2296 Unrenforced structure 0 58, , , , , , ,42 221, , , ,797 Table 11 Dsplacement and Base-force of renforced structure wth shear wall Dsplacement 0 0, , , , , , , renforced structure wth shear wall 0 58,59 145, , , , , ,693 Table 12 Dsplacement and Base-force of renforced structure wth CFRP Dsplacement 0 0,0228 0, , , , Renforced structure wth CFRP 0 63, , , , ,683 The graph below gves the comparson between dsplacements for each structure:

14 194 JOURNAL OF MATERIALS AND ENGINEERING STRUCTURES 3 (2016) Comparson between maxmum Dsplacement for each structure Unrenforced structure structure renforced by CFRP Structure renforced by shear wall Dsplacement (m) Fg. 13 Comparatve graph of the maxmum dsplacement for the three structures 6 Concluson Based on ths study, the more sutable technque for the retrofttng of s the one usng the CFRP. In addton to the gan n ductlty, capacty bearng and consderable decreasng n dsplacement provde by carbon fber, ths knd of fbers have excellent propertes for structural members as hgh strength, hgh elastc modulus, hgh durablty, and lght weght. Unlke the renforcement by shear wall, t ncrease consderably the weght of the structure and take a lot of tme to realze t and t s very expansve compared wth CFRP. REFERENCES [1]- RPS 2000 : Règlement de constructon parassmque, Mnstère de l ATUHE, Secrétarat d État de l Habtat, Royaume du Maroc, [2]- A; El Ghoulbzour, B. Kss, A. Khamlch, Relablty Analyss of Renforced Concrete Buldngs: Comparson between FORM and ISM. Proceda Engneerng. 114 (2015) do: /j.proeng [3]- Appled Technology Councl, ATC-40. Sesmc evaluaton and retroft of concrete Buldngs, Calforna, 1996; Vols. 1 and 2. [4]- Federal Emergency Management Agency (FEMA), 1997.NEHRP provsons for the sesmc rehabltaton of buldngs. Rep FEMA 273 and 274. Washngton, DC : FEMA. [5]- CEN European Commttee for Standardzaton. Eurocode 8. Desgn of structures for earthquake resstance. Doc CE N/TC250/SC8/N335. DRAFT No 6. January. Brussels [6]- Decreto P.C.M. 3274, Prm element n matera d crtergeneral per la classfcazonessmca del terrtoro nazonale e d normatvetecnche per le costruzon n zona sísmca, (In talan). [7]- A. Sharma, G.R. Reddy, K.K. Vaze, R. Elgehausen, Pushover experment and analyss of a full scale nonsesmcally detaled RC structure, Eng. Struct. 46(2013) do: /j.engstruct [8]- A.K. Marsono, N.K. Subed, Analyss Of Renforced Concrete Shear Wall Structures Wth Staggered Openngs Part II Non-Lnear Fnte Element Analyss (NLFEA). In: Proceedng of the 4th Asan-Pacfc Structural Engneerng and Constructon Conference (APSEC2000). September 13th-15th, Kuala Lumpur. p [9]- M. Fntel. Performance of Buldngs Wth Shear Walls n Earthquakes of the Last Thrty Years. PCI Journal, 40(3) (1995) [10]- S.A. Shekh, G. Yau, Sesmc behavor of concrete columns confned wth steel and fbre renforced polymers. ACI Struct. J. 99(1) (2002) [11]- R.D. Lacobucc, S.A. Shekh, O. Bayrak, Retroft of square concrete columns wth carbon fbre renforced

15 JOURNAL OF MATERIALS AND ENGINEERING STRUCTURES 3 (2016) polymer for sesmc resstance. ACI Struct. J. 100(6) (2003) [12]- Amercan Socety of Cvl Engneers (ASCE), Prestandard And Commentary for the Ses mc Rehabltaton of Buldngs, Report No. FEMA-356, Federal Emergency Management Agency, Washngton, D.C. [13]- B.D. Reddy, Th. J; Sngh, Evaluaton of nonlnear statc procedures n the sesmc desgn of renforced concrete buldngs. Int. J. Cv. Eng. Tech. 6(8) (2015) [14]- G. Wu, Z.T. Lü, Z.S. Wu, Strength and ductlty of concrete cylnders confned wth FRP compostes. Constr. Buld. Mater. 20(3) (2006) do: /j.conbuldmat [15]- M. Mouzzoun, O. Moustach, A. Taleb, Assessment of the behavor factor for sesmc desgn of renforced concrete buldngs. J. Mater. Envron. Sc. 4 (1) (2013) (n French).